Support tube for windings of shrinkable filaments

ABSTRACT

A heat-shrinkable support tube for yarn, constructed of a thermoplastics material which shrinks uniformly under the influence of heat.

United States Patent 7 21 Inventor Alexandre Boutonnet Tassin, France [21] App1.No. 550,273

[22] Filed May 16, 1966 [45] Patented Jan. 12, 1971 [73] Assignee Socmte Rhodiaceta Paris, France a French Body Corporate [32] Priority May 25, 1965 3 3 France [54] SUPPORT TUBE FOR WINDINGS OF SHRINKABLE FILAMENTS 9 Claims, 8 Drawing Figs.

52 U.S.Cl ..242/11s.11, 242/118.2, 242/159 51 1 Int. Cl B65h 75/24 [50] Field ofSearch 242/118.2, 118.11,118.1,118,118.3,118.31,1l8.32;

129, (Glassfibers, Resins, Teflon, Digests) Primary Examiner-George F. Mautz AttorneyCushman, Darby & Cushman ABSTRACT: A heat-shrinkable support tube for yarn, constructed of a thermoplastics material which shrinks uniformly under the influence of heat.

PATENTEB JAN I 2 I9" Areyg wherein L, is the initial length of the element at ordinary temperature, L, is the length of the shrunk element at the treatment temperature envisaged.

It is known that certain filaments, in particular those made from synthetic polymers, are shrinkable under the influence of heat at shrinkage potentials which may attain approximately percent, and that they require to be stabilized by shrinkage treatment before being supplied to the consumer, so that they will not be subjected to dimensional modifications during subsequent utilization. This shrinking treatment is effected by the action of heat and by any appropriate means such as stoving, passage of the filament or yarn over a heating plate or heating rolls, or steam treatment, and it may also take place during other operations such as dyeing, scalding, degreasing, etc.

When it is desired to thermally shrink continuous yarns, it is generally preferred to wind the yarns on a support which will collapse under the pressure of the yarn as it is withdrawn. For this purpose, it has been proposed to use deformable cardboard tubes, the deformations taking place at random on the surface of the tube along purposely weakened lines. Experiment has shown that these tubes are in fact deformed in a completely irregular manner. Consequently, the yarn is not uniformly shrunk and sometimes the winding, since it no longer has any hold, collapses.

Tubes have also been proposed which are rigid and are made of metal or a plastics material and the surface of which is formed with longitudinal slots which are in quincunxial arrangement and the length of which is less than that of the tubes; these slots permit radial contraction of the tubes. The tubes are complicated to manufacture, and, during the retraction, the closing of the lips of the slots nips the turns of yarn adjacent the tube and this damages the yarn and may even cut it.

At the present day, tubes are known which comprise an undeformable, tubular inner portion and a deformable, coaxial, tubular portion the diameter of which is greater than that of the first portion and the edges of which are rolled and stuck on the inner tube. In addition to the fact that these tubes are complicated to manufacture, they have a further considerable disadvantage; after retraction, the deformable portion supporting the filaments is flattened against the rigid portion, but the edges retain their initial position, so that the filaments located at the edge and near the tube are unsatisfactorily shrunk and are locked by the deformed tube, so that complete winding off is rendered impossible and a considerable loss of yarn is incurred.

The present invention provides a support tube for windings of shrinkable yams, the said tube itself being made from a thermoplastics material which shrinks uniformly under the influence of heat.

The tube according to the invention may be made from a material which is identical with or which differs from that of the shrinkable yarns, provided only, that it holds well at the temperature at which the shrinking is effected. Among the materials from which the tubes according to the invention can be made, are shrinkable thermoplastics substances such as polyesters or acrylic polymers and the polyamides or interpolyamides, which are especially suitable.

The tube according to the invention may have a surface of revolution which may advantageously be cylindrical or frustoconical. The outer surface would have no roughened portions which might fray or catch in the yarn. The thickness of the tube wall must of course be sufficient to give the tube a good hold under the influence of the weight of the winding which it will be required to support.

The shrinking power of the tube according to the invention may vary within relatively wide limits. Preferably, it is between 5 and 20 percent, these limits corresponding to the minimum and maximum values of the shrinkingpotential of those thermoplastics materials which are suitable for the manufacture of the said tube, at temperatures ranging between approximately 65 C. andapproximately C. Thiswide range of possible shrinkage permits especially advantageous utilization of a tube of this kind; it is possible to select a shrinking power which corresponds substantially, at the shrinkage temperature envisaged to that of the yarns to be shrunk. It may also be selected at a slightly lower value in such manner as to improve the ability of the winding to retain its form on the tube,

without involving at the same time a degree of tension which would damage the filaments adjacent the tube. On the-other hand, it is sometimes advantageous to select for the tube a shrinking power which is slightly greater than that of the yarn, in particular if it is desired to remove the tube after shrinking, so as to obtain a sleeve.

The invention further provides a method of stabilizing a shrinkable filament in which the filament is wound on a support tube of the invention and the filament and support tube are then subjected to a heat shrinking treatment.

The support tube may be selected practically at will, i.e. in accordance with the shrinking power of the yarn to be treated at the temperature and in accordance with the object to be achieved.

In order that the invention may more readily be understood, the following description is given, merely by way of example, with reference to the accompanying drawings in which:

FIGS. 1, 3, 5 and 7 are front elevations of four embodiments of support according to the invention; and

FIGS. 2, 4, 6 and 8 are end elevations of the supports of FIGS. 1,3, 5 and 7 respectively.

The self-shrinking support tube 10 illustrated in FIGS. 1 and 2 is in one piece, formed for example by extrusion of a thermoplastics substance in the fused state and in the form of a tube which is then subjected to radial stretching or expansion at a relatively low temperature (preferably at room temperature), the tube then being cut into sections of predetermined length. In this case, the shrinking power of the completed tube depends on the rate of expansion and on the basic polymer.

The support tube 11 illustrated in FIGS. 3 and 4 consists of a flat element the two opposite edges 12, 13 of which are welded or stuck together, the weld or sticking line constituting a generatrix of the tube obtained. For this purpose, it is possible for example to extrude or pour a continuous strip of thermoplastics material, which said strip is then longitudinally stretched.

The flat element may be cut from the stretched strip and then wound in such a manner as to obtain, by welding or sticking, a cylinder or a frustum of a cone the generatrices of which must be orthogonal to the direction of stretching of the strip.

In the embodiment of FIGS. 5 and 6 the stretched strip, formed as above, is wound in simple, contiguous helical turns which are secured together along the helical line 15 by cold sticking, by continuous welding or spot-welding, or by means of a thermostable adhesive tape. Finally, the tube 16, thus formed, is cut into sections of predetermined length.

The support tube according to the invention may also comprise a multiplicity of layers obtained as discussed hereinabove. The resulting tube has the greater degree of solidity which is necessary for example for large windings. An example of this type of support is shown diagrammatically in FIGS. 7 and 8. In this case, the tube 17 consists of two layers l8, 19 formed by means of two strips wound in opposite directions and secured along the helical lines 20, 21 as before.

The shrinking power of a helically wound tube depends not only on the shrinking potential of the initial strip, i.e. the

material of which it consists and the amount of stretching to which it is subjected, but also on its winding angle. The adjustment of these factors is within the competence of the person skilled in the art and it is the flexibility of the said adjustment which permits a considerable degree of diversification of the tubes to satisfy specific requirements.

An interesting variant of the invention consists of a tube as described hereinabove, which is perforated in known manner and can thus be used for dyeing purposes and during the various modes of treatment involving the use of hot circulating liquids. This possibility permits the utilization of a thermal treatment for the shrinking of shrinkable yarns simultaneously or after a further treatment, for example a dyeing treatment, the two operations being effected on the same support, and thus avoiding a change in the presentation of the yarn and the manipulations involved therein.

An essential advantage of the present invention resides in the possibility of utilizing a support tube the shrinking power of which corresponds substantially to that of the yarn to be shrunk; in fact, once the yarn has been wound it is no longer subjected to any stressing derived from the support, this applying in particular to the turns in the immediate vicinity of the 1 tube. Since, furthermore, the latter shrinks in an entirely uniform manner both at the ends of the tube and in the center thereof, a yarn is obtained which is shrunk uniformly over its entire length and which can be completely wound off under excellent conditions. Furthermore, a tube of this kind is able to carry yarn reserves permitting the successive attachment of the yarns of a multiplicity of tubes, this being especially useful in warping and spooling operations. Finally, uniform shrinkage of the yarn imparts to the latter a dyeing affinity which is more uniform.

All the shrinkable yarns may be treated on the tube supports according to the invention, i.e. polyamide, polyester, polyacrylic, triacetate, vinyl polychloride, polypropylene yarns, etc.

' The following examples are given purely by way of illustration and shall not be deemed to any way limit the invention.

EXAMPLE 1 p A copolymer containing 95 percent by weight of polycaprolactam and 5 percent of polyadipate of hexamethylenediamine was extruded. in the form of a strip 60 mm. wide which was longitudinally stretched at a rate of 3.8. This strip, 7/10 mm. thick, was then wound in single, contiguous turns and was spot-welded. On sections of the tube thus obtained, 36 mm. in diameter, windings of 900 g. of polyester filament, 130 denier/66s having 200 S-tums were mounted. The windings were then subjected to steaming at 130 C. for 1 hour.

After steaming, it was found that the shrinkage of the tube was 1 1.3 percent, whereas that of the yarn was 11.8 percent. The windings obtained retained their shape extremely well; the shrunk tube was definitely cylindrical and the residual shrinkages of the yarn were satisfactorily homogeneous, in particular in respect of the portions of yarn in contact with the tube. The windings could be unwound under extremely satisfactory conditions.

EXAMPLE 2 A copolymer as described in example 1 was extruded in the form of a strip 69 mm. wide, which was then longitudinally stretched at a rate of 3.74. This strip, 5/10 mm. thick, was then wound in single, contiguous turns.and was welded edge to edge. From the tube thus obtained, sections 170 mm. long, 36 mm. in diameter and 0.5 mm. thick were cut and on these there were mounted windings of 900 g. of polyester yarn, 130 denier/66s having 200 S-turns. These windings were subjected to steaming at 110 C.,for 1 hour.

After treatment, a yarn was obtained which was shrunk uniformly by 8.6 percent. The windings could be wound off under extremely good conditions, since the tube had uniformly shrunk by 8.1 percent.

1 claim:

1. A support tube for windings of shrinkable yarns, said tube itself being formed from a thermoplastics material which has been previously longitudinally stretched and which shrinks uniformly under the influence of heat and having an outer surface being a surface of revolution and side edges, said side edges being helically disposed and mutually fixedly attached.

2. A support tube for windings of shrinkable yarns, said tube itself being formed from a thermoplastics material which shrinks uniformly under the influence of heat, said tube comprising two tubular elements disposed one internally of the other, each of said tubular elements having an outer surface,

each being a surface of revolution, and a pair of side edges, said side edges being helically disposed and mutually fixedly attached, the helices defined by the pairs of side edges of each of the tubular elements being in mutually opposite senses.

3. In combination, a support tube formed from thermoplastics material which shrinks uniformly under the influence of heat, and a yarn wound around said tube, said yarn being composed of the same material as said tube.

4. In combination, a support tube formed from a thermoplastics material which shrinks uniformly under the influence of heat, and a yarn wound around said support tube, said yarn and said tube having substantially the same shrinking potential.

5. A support tube for windings of heat-shrinkable yarns, said tube itself being formed from a prestressed thermoplastics material which shrinks unifomily under the influence of heat.

6. A support tube as specified in claim 5, wherein the heatshrinking potential of the tube is between 5 percent and 20 percent.

7. A support tube as specified in claim 5, in which means defining perforations are provided in said tube.

8. A support tube for windings of heat-shrinkable yarns, said tube itself being formed from a thermoplastics material which shrinks uniformly under the influence of heat, said tube comprising an outer surface of revolution, longitudinally extending opposite edges, means mutually fixedly attaching said edges together along a sticking line, said sticking line being a generatrix of said surface of revolution, and wherein said tube is radially stretched.

9. A support tube for windings of heat-shrinkable yarns, said tube itself being formed from a thermoplastics material which shrinks uniformly under the influence of heat, said tube comprising an extruded, radially stretched tubular element. 

1. A support tube for windings of shrinkable yarns, said tube itself being formed from a thermoplastics material which has been previously longitudinally stretched and which shrinks uniformly under the influence of heat and having an outer surface being a surface of revolution and side edges, said side edges being helically disposed and mutually fixedly attached.
 2. A support tube for windings of shrinkable yarns, said tube itself being formed from a thermoplastics material which shrinks uniformly under the influence of heat, said tube comprising two tubular elements disposed one internally of the other, each of said tubular elements having an outer surface, each being a surface of revolution, and a pair of side edges, said side edges being helically disposed and mutually fixedly attached, the helices defined by the pairs of side edges of each of the tubular elements being in mutually opposite senses.
 3. In combination, a support tube formed from thermoplastics material which shrinks uniformly under the influence of heat, and a yarn wound around said tube, said yarn being composed of the same material as said tube.
 4. In combination, a support tube formed from a thermoplastics material which shrinks uniformly under the influence of heat, and a yarn wound around said support tube, said yarn and said tube having substantially the same shrinking potential.
 5. A support tube for windings of heat-shrinkable yarns, said tube itself being formed from a prestressed thermoplastics material which shrinks uniformly under the influence of heat.
 6. A support tube as specified in claim 5, wherein the heat-shrinking potential of the tube is between 5 percent and 20 percent.
 7. A support tube as specified in claim 5, in which means defining perforations are provided in said tube.
 8. A support tube for windings of heat-shrinkable yarns, said tube itself being formed from a thermoplastics material which shrinks uniformly under the influence of heat, said tube comprising an outer surface of revolution, longitudinally extending opposite edges, means mutually fixedly attaching said edges together along a sticking line, said sticking line being a generatrix of said surface of revolution, and wherein said tube is radially stretched.
 9. A support tube for windings of heat-shrinkable yarns, said tube itself being formed from a thermoplastics material which shrinks uniformly under the influence of heat, said tube comprising an extruded, radially stretched tubular element. 